Apparatus for filtering slimes.



G. BUTTERS. APPARATUS FOR FILTEBIN'G SLIMES.

APPLICATION FILED JUNE 11 1913.

Patented June 16, 1914;

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G.BUTTERS. I APPARATUS FOR FILTERING SLIMES.

APPLICATION FILED JUNE 11, 1913.

Patented June 16, 1914.

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COLUIIIA PLANOGIAPN CD" WASHINGTON, D. C.

UNITED STATES PATENT OFFICE.

CHARLES BUTTERS, OF OAKLAND, CALIFORNIA;

APPARATUS FOR FILT'ERING SLIMES.

To all whom it may concern Be it known that I, CHARLES BUTTERS, acitizen of the United States, and a resident of Oakland, county ofAlameda, State of California, have invented certain new and usefulImprovements in Apparatus for Filtering Slimes, of which the followingis a specification.

The object of my invention is to shorten the time taken for a cycle ofoperation in the process of filtering valuable compounds, such asslimes, which result from the well known cyanid process of treatingores.

Another object of my invention is to lower the cost of filter leaveswhile at the same time increasing their life and value.

In abstracting the values from slimes one of the most difiicult andtroublesome prob lems is to dislodge reliably and within an economicaltime, the slime cake from the surface of the filter medium after thefiltering process has been completed, without injuring the filtersurface of the leaf.

It has been the practice heretofore to dislodge slime cakes by airpressure placed on the interior of the leaves while suspended in theair, or this has been accomplished in some cases by water under pressurebeing passed through the filter medium in a direction reverse to that ofthe filtrate. It has been supposed hereto-fore that to dislodge the cakereliably and Within an economical time, pressure was necessary whetherof air,

water or other fluid in the dislodging step, and special precaution hassometimes been taken to get a uniformly thick, cohesive and resistantcake deposit such that the fiuid under pressure might dislodge it as anentirety and make it unnecessary to use additional means to dislodge thecake completely. By my process such uniformity of the cake is of noimportance at all to the cake dis- .lodgment, and consequently thefiltering operation may be more economical.

If notable internal pressure is put on a leaf for cake-dislodgmentpurposes, means must be provided to prevent distension or ballooning ofthe filter medium. Various means have been devised to this end, all ofwhich have added to the difficulty of cakedislodgment. As a matter ofpractice, too, it is found that all such means are a hindrance to properand economical operation; further, they shorten the life of the leaves,but have been regarded as indispensable Specification of Letters Patent.

Application filed June 11, 1913,

Patented June 16, 1914.

Serial No. 772.945.

when former practicable methods of cakedislodgment have been used.

The efiiciency of the leaves heretofore used is low, first, because aconsiderable amount of the surface of the filter medium is obstructed bythe means used to prevent ballooning, such as strips down the sides; andsecond, because of stitching the media together or by bolting stripsonto the outside of the leaf to prevent ballooning, comparatively largeholes are made in the media. Also, these holes make the media moreliable to rupture under internal pressure, thus shortening their life.

I have discovered that pressure is unnecessary to reliablecake-dislodgn'lent within an economical time, and that complete successcan be attained by saturation of the entire area of the filter medium.It is found in practice that these cakes have unusual adhesion andcohesion, and that when a cake is formed on each side of a filter leafthey are not easily dislodged. Due to the great cohesion of the cake itis very important that the upper part, as well as the other parts, ofthe filter medium be saturated in the dislodging step, as it is foundthat the adhesion of the cake to the medium is greatly lessened, andthat the time for dislodgment is materially shortened thereby. This hasnot been attained in leaves heretofore constructed because theycontained enough air to prevent water teaching the top part thereof evenwhen admitted under pressure. This was true in spite of the fact thatthe leaf might be under vacuous conditions at the time the ater wasfirst admitted.

In some cases it is found advisable to admit the water (for dislodgingthe cake by saturation of the filter media) into the leaf withoutpressure and more or less slowly, and in order to do this I make use ofa con nection to the water supply by which the water going into the leafcannot be under pressure, and, therefore, nopressure can be exertedinside the leaf. I have, therefore, devised av leaf which cannot haveinternal pressure applied thereto during the dislodging step since by myinvention the cake can be dislodged within a practicable and economicaltime without any internal pressure whatever. It is understood that thecake may be, and preferably is, dislodged while the leaf is submerged inwash water. This means that. there will be considerable hydrol rangedalong the top of the vats and is constatic pressure on the outside ofthe leaf. It has been found by experiment that the dif ference inspecific gravity of the more or less dirty tank wash water and therelatively clean cake dislodging water would be suflicient to maintain acolumn of the relatively clean water inside the leaf several incheshigher than the level of the tank wash water, so that the relief valveand the inlet for the cake-dislodging water may be several inches abovethe surface of the tank wash water without. producing greater pressureinside the leaf than the outside pressure on the leaf.

The above fact is useful in practice as it gives considerable latitudebetween the level of the tank wash water and that of the inlet for thecake-dislodging water, and of the relief valve, thus preventing theentrance of the tank wash water into the leaf, while at the same timepreventing excess of internal pressure. It will be seen, therefore, thatthe external hydrostatic pressure may be balanced but can never beexceeded by the internal hydrostatic pressure.

The above facts make it possible in my type of leaf to saturate theentire filtering surfaces, to use a lighter filter cloth and to dispensewith all manner of bracing, stitching or other surface-roughening meanswhich have heretofore been necessary to prevent ballooning. The absenceof these means makes the caked1slodgmg problem an easler one.

Other advantages will be apparent from the following detaileddescription taken in connection with the accompanying drawings, in whichFigure 1 shows a diagrammatic plan view of a general layout showing aclean water source and piping for supplying the water to the leaves;Fig. 2 is a side elevation of the devices shown in Fig. 1; Fig. 3 is aplan of a portion of a vat with several leaves therein; Fig. 4 is a viewof a leaf embodying my invention; Fig. 5 is a plan view of a reliefvalve; and Fig. 6 is a section of a relief valve.

In Fig. 1. are shown a plurality of vats 1 in which the leaves 2 areplaced as shown in Fig. 3. These leaves are connected with the cleanwater source 3 by means of the piping 4, 5, 32 and the funnel 30. Theleaves are connected with the vacuum-pump by means of the pipe 33 andconnections 6. Between the connections 6 and the pipe 33 is a valvemember 35 and a glass section 36. The valves 35 may be used to cutoffany leaf. By means of the glass 36 the color of the filtrate can beobserved. The pipes 1, 5 and may be suitably supported, as for instance,by the member 3 1 attached to the side of the vat 1. In order that thewater may reach all of the leaves quickly the pipe 5 as arnected withthe pipe 4: from the water supply by means of risers 7 In pipe 41- isplaced the valve 8 by which the clean water supply for cake-dislodgingpurposes may be controlled. .ln the pipe leading to the vacuum-pump, isplaced the valve 9 by which the pump may be connected with, ordisconnected from, the leaves as desired. The pump 10 is shown connectedwith the pipe for the purpose of creating a vacuum within the leavesduring the filtering operation, also during the cake-washing period.

When it is desired to begin the filtering operation, the valve 8 isclosed, the valve 9 opened and the pump 10 started to decrease thepressure within the filter leaves, and thereby draw a filtrate throughand form a cake on the surface of the filter medium. lVhen suflicientcake has been forn'ied, it may be treated in well known ways with barrensolution and then with wash water, and it is then ready to be dislodged.The valve 9 may then be closed and the valve 8 is opened therebypermitting the water to run into the leaves from the tank 3 through thepiping 4c, risers 7, pipes 5 and 32 and funnel 30, thus filling theleaves, and causing the cakes to drop within four or five minutes. Theair contained in the leaves is discharged through the relief vaves 11.The thick slime is then run out from the bottom of the vats into therun-way 12, and thence to the slime-pit. The vats may be properlysupported by any convenient means such as the pillars 1.3 and I-beams1.4:, shown in Fig. 1.

As shown in Fig. &, the leaf comprises a frame having members 15, 16, 17and 18, preferably of tubing. Over this frame is secured a filter medium19 of canvas or other suitable material. Inside the filterleaf is afibrous filler 20 preferably of cocoa mat, for holding the sides thereofapart when vacuum is created within the leaf. The lower frame member 15is perforated or slotted along its upper side and is connected to avacuum pump 10, or other pressure-decreasing means through the righthandend member 16, the connection 6 and the pipe 33. The connection 6 may beof any suitable material preferably of rubber. The filtrate is removedfrom the leaf by means of the pump through these connections. Theleft-hand frame member 17 is plugged by any suitable means such as awood plug shown at 21 in Fig. 1. The top frame member 18 is perforatedor slotted along its lower side and to this member is attached therelief valve 11. This member is also plugged as shown at 28, and isrigidly connected to the right-hand end member to make a rigid framestructure. It is not necessary that the relief valve be connected to theframe member, but this arrangement liZt) um is on leaves, andconsequentlythe balls is preferred and it is so illustrated'in the!drawings. The pipe 22 connecting the valve i to the leaf may be of anysuitable len th. The relief valve 11 should be connecte to i the upperportion of the leaf in order to; allow the escape of air.

Connected by any suitable fixture 29 toi the members 6 and theright-hand end frame member 16 is a funnel 30. Placed within. thisfunnel is a ball or other valve member 31. At the proper points alongthe piping 5 are arranged pipes 32 adapted to discharge water into thefunnels and therethroug h into the leaves. These pipes get their watersupply from the tank 8 as heretofore described. Vhen it is desired toadmit water into the leaf for dis'lodging the cake the valve members 31will be removed from the funnels so that water may readily pass into theleaves. The function of the balls or other valve members is to preventthe entrance of air into the leaves while the vacuwill be replaced inthe funnels when it is desired to begin the filtering. For the purposeof illustration the valves are shown in the funnels but other forms ofvalve may. be used provided there is an opening to atmosphere in theclean water supply pipe near its point of attachment to the leaf inorder to prevent internal pressure within the leaf. By the use of thismeans it will be seen that no internal pressure in the leaf is possiblewhile at the same time the air will be prevented from entering the leafduring the time vacuum is on, and also the air contained in the leaf, atthe time it is desired to discharge the cake, will be permitted toescape through the relief valve 11, when the clean water is admitted andbegins to fill up the leaf. This action is due to the difference inspecific gravity of the tank wash water, the clean cake-dislodgingwater, and the air, as will be readily understood. By allowing the leafto be filled comparatively slowly with water the air will have time toescape from all parts of the leaf without being entrapped, as a resultof which the filter medium will be completely saturated and the cakewill be readily dislodged after the water has completely filled theleaf.

The preferred form of relief valve is shown in detail in Figs. 5 and 6,but other kinds of valve may be used provided they allow exit butprevent entrance of air. The valve hereafter described is by way ofexample only and must not be considered as limiting my invention. Asshown in Figs. 5 and 6, the relief-valve consists of a pipecoupling 23around which is securely clamped a. rubber tube 24, the upper end ofwhich acts as a valve seat. This tube is clamped around the coupling 23by a band 25 in any well known manner. Arranged to coiiperate with theseat 24 is a ball 26 of rubber. For the purpose of confining themovement of the ball, guards 27 are placed around same, as clearly shownin the drawing.

will :be readily understood that by the of a valve of the kind abovedescribed, the entrance of air will be entirely prevented when vacuumislcreated within the leaf,

thereby not interfering in any way with the filtering properties oftheleaf. As soon as the vacuum is relieved, the elasticity of the seat willpush the ball up, and due to un avoidable irregularities, small passageswill exist between the ball. and its seat sufficient to allow the escapeof whatever air remains in the leaf as water is admitted thereto. Bythis arrangement the air may be easily displaced by water when the;latter is admitted to the leaflso that it can saturate the entiresurface of the filter media, and cause rapid dislodgment of the cake.The water for this purpose is supplied from any suitable supply 3 asheretofore described.

In Fig. 3 is illustrated a series of leaves ,2 placed on the sides of avat, l.

The operation of my device is as follows :The leaf is completelysubmerged, care being taken not to allow slimes to enter therelief-valve or the funnel. The balls are placed in the funnels. Suctionis applied to the interior of the leaf by any means, such as avacuum'pump, and the filtrate is carried off by the pressure-decreasingmeans. As soon as the internal pressure is decreased, the reliefvalveand the funnel-valve close tight so as to completely prevent theentrance of air. The suction is continued until a cake of properthickness is deposited on the filter surface. This cake may then bevariously treated with barren solution and wash water, and then thevacuum is turned off, the valve members are moved from the funnels, andwater is introduced through pipes 32 into the funnels, and is conductedinto the bottom frame'member 15, the leaf being still submerged. As thewater rises in the leaf, the air passes out through the relief-valve 11so that the water rises to the top of the leaf, completely fills it andso saturates the entire surface of the filter media, thereby causing thecake to be rapidly dislodged. The filter medium is thereby cleansed, andis ready for another cycle.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is

1. In a suction filter leaf, the combination of a frame, filter mediacarried thereby and a water supply pipe for cake dislodging purposesconnected to said leaf, said pipe having an opening to atmosphere nearits point of attachment to the leaf.

2. In a suction filter leaf, the combination of a frame, filter mediacarried thereby, a

&

Water supply pipe for cake dislodging purposes connected with said leaf,and a funnel in said pipe near its point of connection to said leaf.

3. In a suction filter leaf, the combination of a frame, a filter mediacarried thereby and a water supply pipe for cake dislodging purposesconnected to said leaf, said pipe having a. valve-controlled openingtherein near the pointof attachment of said pipe to the leaf.

4. In a suction filter leaf, the combination of a frame, filter mediacarried thereby, a water supply pipe connected to said leaf, a funnelplaced in said pipe near its connection with said leaf, and a valve insaid funnel.

5. In a suction filter leaf, the combination of a frame having passagesin certain members thereof, a water supply pipe for cake 'dislodgingpurposes connected with the bot tom frame member, said pipe having a funnel therein, and a relief valve connected to said leaf.

Copies of this patent may be obtained for 6. In a suction filter leaf,the combination of a frame having passages connected with the interiorand exterior of said leaf, filter media therefor, a relief valveconnected with the upper portion of the leaf, a water supply pipe forcake dislodging purposes connected with the lower portion of said leafand means for preventing pressure in said pipe.

. 7. In suction filter leaf, the combination of a frame, the top andbottom members of said frame being perforated and opening internally ofsaid leaf, an automatic relief valve connected with said upper member,and a water supply pipe connected with the lower member, a funnel insaid pipe, and a ball valve in said funnel.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

CHARLES BUTTER-S.

itnesses NEWTON A. BURGESS, EDWIN SEGER.

five cents each, by addressing the Commissioner of Patents, Washington,D. G.

